Grand-piano construction



Aug. 27, 1929. B. c. EDMANDS GRAND PIANO CONSTRUCTION Filed April 7. 1926 2 Sheets-Sheer.

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Inveni'ov:

Patented Aug. 27, 1929.

UNITED STATES PATENT OFFICE.

BRADFORD C. EDMANDS, OF NEWTON, MASSACHUSETTS, ASSIGNOR TO AMERICAN PIANO COMPANY, OF NEW YORK, N. Y., A CORPORATION OF NEW JERSEY.

GRAND-PIANO CONSTRUCTION.

Application filed April 7, 1926. Serial No. 100,215.

This invention relates to the art of constructing grand pianos and has as an object to improve the construction thereof and to improve the method of assembling such pianos.

For many years, in the manufacture of grand pianos, it has been customary to build a wooden skeleton frame, then apply the laminated case rim thereto, and subsequently fit the sounding board, bridges, string plate, strings and other parts into place withinthe rim. This method involves many constructional difficulties and calls for much painstaking and skilled workmanship to fit the various parts together and to fit them accurately within the internal surface of the case rim.

It has been proposed heretofore to eliminate some of these constructional difficulties, by assembling the skeleton frame and its immediately associated parts such as the sounding board, bridges, string plate and strings, and to separately construct the laminated case rim, and then to apply the case rim to the previously assembled skeleton frame unit, the outer perimeter of the skeleton frame being cut accurately to fit the inner surface of the case rim and being rigidly secured thereto.

It has also been'proposed, as an improvement on the foregoing method, to construct the skeleton frame with outer dimensions somewhat smaller than the inner dimensions of the case rim, and to provide a rib or ledge attached to the rim on which the skeleton frame might seat. The skeleton frame was then secured to the rib or ledge by providing spacing wedges between the skeleton frame and case rim through which the two might be rigidly connected by suitable screws at several points along the outer periphery of the skeleton frame.

It will be noted that in each of the previously described methods and constructions the skeleton frame and hence the sounding board are rigidly secured to the case rim either around the entire periphery of the skeleton frame or at numerous pointsaround the entire periphery. According to the present invention it is proposed to secure the skeleton frame directly to the case rim along only a small portion of its periphery, leaving the other edges of the skeleton frame substantially free.

The invention will be best understood from a specific description of an illustrative structure and a preferred method of assembling such structure, and the accompanying drawings illustrate a preferred embodiment of the invention.

Figure l is a perspective view of the case rim of a grand piano.

Figure 2 is a perspective View of a skeleton frame adapted to fit within the rim of Figure 1.

Figure 3 is a central sectional View of the skeleton frame with the sounding board, string plate and strings assembled thereon.

Figure 4 is a similar sectional view showing the skeleton frame unit inserted within the case rim.

Figure 5 is a plan view showing the skeleton frame and rim in assembled relation.

Figures 6, 7 and 8 are detailed sectional views taken on the line 6-6, 77 and 88 respectively of Figure 5.

In the construction illustrated the case rim unit and skeleton frame unit are made separately and afterward assembled.

he case rim unit (see Figure 1) comprises a rim proper 1 having a rib or ledge 2 extending around the interior thereof preferably adjacent the lower edge, said rib or ledge being provided to stiffen the rim during the process of manr ufacture, and also to provide a support for Cir the skeleton frame when the same is inserted within the case rim. The key bed 3 and the front bar 4 are secured to the rim to brace the ends and to hold them in proper spaced relation. This case rim unit may be finished complete and may be stained, varnished and polished before any of the other parts are assembled therewith.

The skeleton frame 5 (see Figure 2) may be separately constructed and is of usual construction except that one side 6 of the frame is of slightly heavier construction and is provided with a flat outer surface which may fit against the flat inner surface 7 of the case rim. The ends of the skeleton frame are connected by the usual bar 8, and

the'usual central bar 9 and diagonal brace 10 may be cut away if necessary to fit over the rib or ledge 2.

A leg support 11 may be attached to the ease rim and preferably also to the central bar 9 of the skeleton frame after the two are assembled.

After the skeleton frame shown in Figure 2 is assembled the remaining parts of the skeleton frame unit such as the sounding board, a, string plate 6 and strings 0 may be secured thereto and the skeleton frame unit may then be inserted in the case rim and allowed to rest on the rib or ledge 2.

Thereafter the end 6 of the skeleton frame may be rigidly secured to the case rim by gluing and by applying the screws 12 passing directly through the frame and into the case rim. Thereafter the skeleton frame may be secured to the rib or ledge 2 by means of the screws 13, and additionally by the screws 14 which secure the leg support to the case rim.

It will be observed that according to the construction just described the skeleton frame and sounding board are fitted to the case rim and secured directly thereto on one side only. Accordingly, the skeleton frame and sounding board are permmitted a certain degree of freedom to vibrate which is not possible where the skeleton frame is rigidly secured to the case rim around its entire outer periphery.

Furthermore, the skeleton frame and sounding board are not subjected to the strains which are produced upon it in old constructions in which the parts are rigidly secured.

It has been observed that grand pianos constructed in this manner provide a different and superior quality of tone from those constructed in accordance with previous methods. It is thought that this result is due to the greater degree of freedom of the sounding board, in that it is permitted to vibrate freely at all points without restriction from the case rim, although other causes such as the absence of strain may also contribute. The difference is easily distinguishable, however, and grand pianos constructed in accordance with the present invention produce a certain purity and freedom of tone not observed in instruments constructed in accordance with old methods.

In addition, the constructional advantages of the improved methods previously described have been retained, whereby the case rim unit and the skeleton frame unit may be separately constructed and afterward assembled.

It is to be understood that the particular method and construction described herein are merely illustrative of the invention as variations will be obvious to those skilled in the art.

I claim as my invention:

1. In a grand piano, a case rim, a skeleton frame, and means to secure said frame to said rim at contiguous points along a portion of its outer periphery only.

I 2. In a grand piano, a case rim, a skeleton frame, and means to secure said frame to said rim at contiguous points adapted to permit slight relative movement between said frame and rim along a substantial portion of the outer periphery of said rim.

3. In a grand piano, a case rim, a skeleton frame, means to secure. said frame to said rim along a portion of its outer periphery only, and means to support said frame around its entire periphery.

41-. In a grand piano, a case rim, a skeleton frame, and means to secure said frame to said rim comprising horizontal screws passing through said frame and rim along a portion of one side of the outer periphery of said frame only.

5. In a grand piano, a case rim, a rib secured to the inner periphery thereof, a skeleton frame having outer dimensions less than the inner dimensions of said case rim and adapted to seat on said rib, and means to secure said skeleton frame directly to said case rim along a portion of one side of its periphery only.

. 6. In a grand piano, a case rim, a rib se cured to the inner periphery thereof, a skeleton frame having outer dimensions less than the inner dimensions of said case rim and adapted to seat on said rib, means to secure said skeleton frame directly to said case rim along a portion of one side of its periphery only, and means to secure said skeleton frame to said rib.

7. In a grand piano, a case rim, a rib secured to the inner periphery thereof, a skeleton frame having outer dimensions less than the inner dimensions of said case rim, and adapted to seat on said rib, and means to secure said frame to said rim comprising horizontal screws passing through said frame and rim along a portion of one side of the outer periphery of said frame only, and means to secure said frame to said rib, comprising vertical screws passing therethrough. i

8. In a grand piano, a case rim, a skeleton frame, said rim and frame having their inner and outer peripheries, respectively, fitted along a small portion only, and means to secure the two along said fitted portion only.

'9. The improvement in the art of constructing grand pianos which comprises constructing and assembling a case rim unit and a skeleton frame unit separately, assembling the two units, and securing the skeleton frame directly to the case rim at contiguous points along a portion of its outer periphery only.

10. The improvement in the art of constructing grand pianos Which comprises constructing and assembling a case rim and skeleton frame, and fitting the two along a portion of the outer periphery of said frame 10 only and securing the two along the fitted portion only, while leaving the remainder of said periphery free to vibrate independently of said case rim.

In testimony whereof, I have signed my 15 name to this specification this twenty-ninth day of March, 1926.

BRADFORD G. EDMANDS.

CERTIFICATE OF CORRECTION.

Patent No. 1,725,904. Granted August 27, 1929. to

BRADFORD C. EDMANDS.

Signed and sealed this 1st day of October, A. D. 1929.

printed specification of the ws: Page 2, line 72, claim and line 78, claim 3, after the ints"; and that the said Letters herein that the same may conform M. J. Moore, (Seal) Acting Commissioner of Patents.

CERTIFICATE OF CORRECTION.

Patent No. 1,725,904. Granted August 27, 1929. to

BRADFORD C. EDMANDS.

It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction as follows: Page 2, line 72, claim 2, strike out the words "at contiguous points", and line 78, claim 3, after the word "rim" insert the words "at contiguous points"; and that the said Letters Patent should be read-with these corrections therein that the same may conform to the record of the case in the Patent Office.

Signed and sealed this 1st day of October, A. D. 1929.

M. J. Moore, (Seal) Acting Commissioner of Patents. 

